1. General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Welcome to Chemistry 121
© 2013 Pearson Education, Inc.

2. Chapter 1 Chemistry and Measurements
General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Chapter 1
Chemistry and Measurements
Lectures
© 2013 Pearson Education, Inc.

3. What is Chemistry? Chemistry is the study of matter and its
composition,
structure,
properties, and
reactions
Chemsitry occurs all around you, for example,
when you
cook food,
add chlorine to your pool,
digest food, and
drop an antacid tablet in a glass of water.

4. Success in Chemistry 121
Regular attendance, active participation in problem solving
Ask questions early and often!
Seek extra help as needed – show up before class, take advantage to tutoring sessions
Follow the suggestions given in chapter one of the text book, learn how to use the different features of your text book

5. Using your textbook Before reading, review topics in Looking Ahead.
Review Learning Goals at the beginning of each section.
Solve Concept Checks to help you understand the key ideas in each chapter.
After reading, work through Sample Problems and try the associated Study Checks.
Work the sets of Questions and Problems at the end of each section.

6. Active Learning
Use Active Learning methods to help you learn chemistry.
Read all assigned materials before you attend lectures.
Note questions you have about the reading to discuss with your instructor
Practice problem solving.
Attend the office hours for help.

7. Form a Study Plan

8. Chemistry and Measurements
General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Chapter 1
Chemistry and Measurements
© 2013 Pearson Education, Inc.

9. Sec. 1.3 Measurement in Science
We use measurements in everyday life, such as
walking 2.1 km to campus,
carrying a backpack with a mass of 12 kg, and
observing when the outside temperature has reached 22 oC.
Notice that all measurements have 2 components
A numerical value
A unit written after the numerical value, to indicate the type of measurement made.

10. Units of Measurement: The Metric and SI Systems
The metric system and SI (Système International)
are used
for length, volume, mass, temperature, and time,
in most of the world, and
everywhere by scientists.

11. Units in the Metric System
In the metric and SI systems, one unit is used for each
type of measurement.
Measurement Metric Base Unit SI Unit
Length meter (m) meter (m)
Volume liter (L) cubic meter (m3)
Mass gram (g) kilogram (kg)
Temperature Celsius (C) Kelvin (K)
Time second (s) second (s)

12. Length Measurement Length uses the unit meter
(m) in both the metric and SI systems.
uses centimeters (cm) for smaller units of length.
The letter “c” in front of the “m” is called a metric prefix and denotes a specific power of 10

13. Converting Between Different Units of Length -- Inches, Centimeters, and Meters
Useful relationships between units of length

14. Volume Measurement Volume is the space occupied by a substance.
uses the unit liter (L) in the metric system.
uses the unit cubic meter (m3) in the SI system.
is measured using a graduated cylinder in units of milliliters (mL).

15. Converting between Quarts, Liters, and Milliliters
Useful relationships between units of volume

16. Mass Measurement The mass of an object is
a measure of the quantity of material it contains.
measured in grams (g) for small masses.
is measured in kilograms (kg) in the SI system.
The standard kilogram for
the United States is stored at
the National Institute of
Standards and Technology.

17. Converting Between Pounds, Grams, and Kilograms
Useful relationships between units of mass

18. Temperature Measurement
measured on the Celsius (C) scale in the metric system,
measured on the Kelvin (K) scale in the SI system, and
18°C or 64°F on this thermometer.
Temperature indicates how hot or cold a substance is, and is

19. Section 1.4 Scientific Notation
is used to write very large or very small numbers.
is used to give the width of a human hair ( m) as
8 x 10-6 m.
for a large number such as hairs is written as
1 x 105 hairs.

20. Writing Numbers in Scientific Notation
A number in scientific notation contains a coefficient between 1 and 10 and a power of 10 and a unit.
When converting a number from standard notation to scientific notation, the decimal point is moved until there is only be one digit to the left of the decimal point
For numbers larger than 1, the power of 10 is positive.
For numbers less than 1, the power of 10 is negative
L = 7.5 x = x L

21. Some Powers of Ten

22. Scientific Notation and Calculators
You can enter a number in scientific notation on many calculators using the EE or EXP key.
Use the (+/−) key to change the value of the exponent from positive to negative.

23. Scientific Notation and Calculators
You can enter a number in scientific notation on many calculators using the EE or EXP key.
Use the (+/−) key to change the value of the exponent from positive to negative.

24. Scientific Notation and Calculators
When a calculator display appears in scientific notation, it is shown as a number between 1 and 10 followed by a space and the power of 10.

25. Scientific Notation and Calculators
To write this number in correct scientific notation, write
the coefficient and use the power of 10 as an exponent.

26. Converting Scientific Notation to a Standard Number
When a number in scientific notation has a positive
power of 10,
move the decimal point to the right for the same number of places as the power of 10 and
add placeholder zeros to give the additional decimal places needed.

27. Converting Scientific Notation to a Standard Number
When a number in scientific notation has a negative
power of 10,
move the decimal point to the left for the same number of places as the power of 10 and
add placeholder zeros in front of the coefficient as needed.

28. 1.5 Measured Numbers and Significant Figures
General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Chapter 1
Chemistry and Measurements
1.5 Measured Numbers and Significant Figures
Lectures
© 2013 Pearson Education, Inc.

29. Representing Measured Numbers
Section 1.5 Measured Numbers and Significant Figures
Representing Measured Numbers
Measured numbers are numbers obtained by using
measuring devices, such as
a scale or analytical balance,
a graduated cylinder,
a clock or stopwatch, or
a ruler

30. Writing down measured numbers
Make sure you write down all numbers in the measurement and include the measurement unit
The number of digits you record will depend on the sentsitivity of the measuring device being used
For example, on a metric ruler with lines marking divisions of 0.1cm, write the length to 0.1 cm and estimate the value of the final number to 0.01 cm by visual inspection (you can estimate one decimal place beyond the smallest increments on the measuring device
The length of the wood shown to the left would be written down as 4.55 cm

31. The Concept of Significant Figures
When making a measurement, the number of digits written down include all the digits you are certain of plus the first estimated digit.
A number is a significant figure if it is
a nonzero number (234 g, 3 SF)
a zero between nonzero numbers.
(50071 g, 5 SF)
a zero at the end of a decimal number. (50.00 m, 4 SF)
the coefficient of a number is written in scientific notation. (2.0 x 103 m, 2 SF)

32. The Atlantic-Pacific Rule For Significant Digits
Imagine your number in the middle of the country
Pacific Atlantic
If a decimal point is present, start counting digits from the Pacific (left) side of the number,
The first sig fig is the first nonzero digit, then any digit after that.
e.g would have 4 sig figs

33. The Atlantic-Pacific Rule For Significant Digits
Imagine your number in the middle of the country
Pacific Atlantic
If the decimal point is absent, start counting digits from the Atlantic (right) side, starting with the first non-zero digit. The first sig fig is the first nonzero digit, then any digit after that e.g. 31, ( 3 sig. figs.)

34. Scientific Notation and Significant Zeros
When one or more zeros in a large number are
significant, they are shown more clearly by writing the
number in scientific notation.
5,000. kg x 103 kg
If zeros are not significant, we use only the nonzero
numbers in the coefficient.
5,000 kg 5 x 103 kg

35. Exact Numbers Exact numbers are
those numbers obtained by counting items.
those numbers in a definition comparing two units in the same measuring system.
not measured and do not affect the number of significant figures in a calculated answer.

36. 1.6 Significant Figures in Calculations
General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Chapter 1
Chemistry and Measurements
1.6 Significant Figures in Calculations
Lectures
© 2013 Pearson Education, Inc.

37. Sec. 1.6 Mathematical Calculations and Significant Figures
The number of significant
figures in measured
numbers are used to limit
the number of significant
figures in the final answer.
Calculators do not provide
the appropriate number of
significant figures.

38. Rounding Off To represent the appropriate number of significant
figures, we use "rules for rounding."
1. If the first digit to be dropped is 4 or less, then it, and all following digits are simply dropped from the number.
2. If the first digit to be dropped is 5 or greater, then the last retained digit of the number is increased by 1.

39. Rounding Off

40. Multiplication and Division
When multiplying or dividing use
the same number of significant figures (SF) as the measurement with the fewest significant figures, and
the rounding rules to obtain the correct number of significant figures.

41. Multiplication and Division
When multiplying or dividing use
the same number of significant figures (SF) as the measurement with the fewest significant figures, and
the rounding rules to obtain the correct number of significant figures.

42. Adding Significant Zeros
Sometimes we add one or more significant zeros to
the calculator display in order to obtain the correct
number of significant figures needed.
Example:
Suppose the calculator display is 4, and you need
3 significant figures.
4 becomes 4.00
1 SF SF

43. Addition and Subtraction
When adding or subtracting, use
the same number of decimal places as the measurement with the fewest decimal places and
the rounding rules to adjust the number of digits in the answer.
one decimal place
two decimal places
calculated answer
final answer (with one decimal place)

44. Sec. 1.7 Metric Prefixes and Equalities
A prefix
in front of a unit increases or decreases the size of that unit.
makes units larger or smaller than the initial unit by one or more factors of 10.
indicates a numerical value.

45. Metric and SI Prefixes
Prefixes that increase the size of the unit:

46. Metric and SI Prefixes
Prefixes that decrease the size of the unit:

47. Daily Values for Selected Nutrients

48. Metric Equalities An equality
states the same measurement in two different units.
can be written using the relationships between two metric units.
Example: 1 meter is the same as 100 cm and 1000 mm.

49. Measuring Length
The metric length of 1 meter is the same length as 10 dm, 100 cm,
and 1000 mm.
Q How many millimeters (mm) are in 1 centimeter (cm)?

50. Measuring Volume

51. Measuring Mass
Several equalities can be written for mass in the metric (SI) system.

52. Sec. 1.8 Solving Problems In Chemsitry Using Dimensional Analysis and Conversion Factors
Dimensional Analysis is a problem-solving method used in science
It depends on your ability to identify the numerical information given by the problem, and your ability to identify the numerical information you are supposed to find when solving the problem.
The link between the known value (given) and the unkown value (find) is called a Converion Factor

53. Equalities Equalities
use two different units to describe the same measured amount.
are written for relationships between units of the metric system; between U.S. units or between metric and U.S. units.
Examples:

54. Equalities and Conversion Factors
Equalities are
written as a fraction.
used as conversion factors.
can be represented with one equality in the numerator and the second equality in the denominator.
Examples:

55. Common Equalities

56. Exact and Measured Numbers in Equalities
Equalities between units of
the same system are definitions with numbers that are exact.
different systems (metric and U.S.) are measurements with numbers that have significant figures.
The equality of 2.54 cm = 1 in. is an exception and considered to be exact.

57. Metric Conversion Factors
We can write equalities as conversion factors.

58. Metric-US Conversion Factors
Metric–US conversion factors are written as a ratio with
a numerator and denominator.
Example:

59. Equalities on Food Labels
The contents of packaged foods
in the U.S. are listed in both metric and U.S. units.
indicate the same amount of a substance in two different units.

60. Percent as a Conversion Factor
A percent factor
uses a ratio of the parts to the whole in a fraction.
uses the same units for the parts and whole.
uses the value 100 for the whole.
can be written as two factors.
Example: A food contains 18% (by mass) fat.

61. Chapter 1 Chemistry and Measurements
General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Chapter 1
Chemistry and Measurements
1.9 Problem Solving
Lectures
© 2013 Pearson Education, Inc.

62. Guide to Problem Solving Using Conversion Factors
There are 4 steps to solving problems with conversion
factors.

63. Steps to Solving the Problem
If a person weighs 164 lb, what is the body mass in
kilograms?
Step 1 State the given and needed quantities.
Analyze the Problem
Step 2 Write a plan to convert the given unit to the
needed unit.
lb US–Metric kilograms
Factor
Given
Need
164 lb
kilograms

64. Steps to Solving the Problem
If a person weighs 164 lb, what is the body mass in
kilograms?
Step 3 State the equalities and conversion
factors.
Step 4 Set up the problem to cancel units and
calculate the answer.

65. Steps to Solving the Problem
If a person weighs 164 lb, what is the body mass in
kilograms?
Step 3 State the equalities and conversion
factors.
Step 4 Set up the problem to cancel units and
calculate the answer.

66. Using Two or More Factors
Often, two or more conversion factors are required to
obtain the unit needed for the answer.
Unit 1 Unit Unit 3
Additional conversion factors are placed in the setup
to cancel each preceding unit.

67. Example: Problem Solving
How many minutes are in 1.6 days?
Step 1 State the given and needed quantities.
Analyze the Problem.
Step 2 Write a plan to convert the given unit to the
needed unit.
days time time min
factor factor 2
Given
Need
1.6 days
minutes

68. Example: Problem Solving
How many minutes are in 1.6 days?
Step 3 State the equalities and conversion factors.
Step 4 Set up problem to cancel units and
calculate answer.

69. Density Density compares the mass of an object to its volume.
is the mass of a substance divided by its volume.
are measured in g/L for gases.
are measured in g/cm3 or g/mL for solids and liquids.
Density expression:

70. Chapter 1 Chemistry and Measurements
General, Organic, and Biological Chemistry
Fourth Edition
Karen Timberlake
Chapter 1
Chemistry and Measurements
1.10 Density
Lectures
© 2013 Pearson Education, Inc.

71. Density Density compares the mass of an object to its volume.
is the mass of a substance divided by its volume.
are measured in g/L for gases.
are measured in g/cm3 or g/mL for solids and liquids.
Density expression:

72. Densities of Common Substances

73. Density Calculations

74. Calculating Density
If a g sample of HDL has a volume of cm3, what is the density, in g/cm3, of the HDL sample? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write the density expression.
Given
Need
0.258 g HDL
0.215 cm3 HDL
density in g/cm3 of HDL

75. Calculating Density
If a g sample of HDL has a volume of cm3, what is the density, in g/cm3, of the HDL sample? Step 3 Express mass in grams and volume in milliliters (mL) or cm3. Step 4 Substitute mass and volume into the density expression and calculate the density.

76. Sink or Float
Ice floats in water because the density of ice is less than
the density of water.
Aluminum sinks in water because its density is greater
than the density of water.

77. Problem Solving using Density
Density can be written as a conversion factor.

78. Problem Solving using Density
Density can be used as a conversion factor.
A density of 3.8 g/mL, can be written as an equality,
or written as conversion factors.

79. Problem: Density as a Conversion Factor
If the density of milk is 1.04 g/mL, how many grams of milk are in 0.50 qt of milk? Step 1 State the given and needed quantities. Analyze the Problem.

80. Problem: Density as a Conversion Factor
If the density of milk is 1.04 g/mL, how many grams of milk are in 0.50 qt of milk? Step 1 State the given and needed quantities. Analyze the Problem.

81. Problem: Density as a Conversion Factor
If the density of milk is 1.04 g/mL, how many grams of milk are in 0.50 qt of milk? Step 2 Write a plan to calculate needed quantity. volume US–Metric density mass factor factor Step 3 Write equalities and conversion factors.

82. Problem: Density as a Conversion Factor
If the density of milk is 1.04 g/mL, how many grams of milk are in 0.50 qt of milk? Step 4 Set up the problem to calculate the needed quantity.

83. Specific Gravity Specific Gravity (sp gr)
is the relationship between the density of a substance and the density of water.
is determined by dividing the density of the sample by the density of water.
is a unitless quantity.

84. Specific Gravity Specific Gravity is measured by an instrument called
a hydrometer.